JP2015203071A - Copolymer having branch structure and copolymer composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a new copolymer having a branch structure for improving moldability of a resin; and a copolymer composition.SOLUTION: There are provided: (1) a copolymer resin composition of a copolymer which is obtained by simultaneously adding a divinylbenzene derivative and a conjugated diene or a divinylbenzene derivative as a branching step and in which an anionic polymer of a vinyl aromatic hydrocarbon monomer has a weight average molecular weight as measured by a GPC method of 20000 to 2000000 using an initiator in which the molar ratio between a divinylbenzene derivative and an alkyl lithium is 3/97 to 80/20, wherein (2) the mass ratio between the copolymer described in (1) and a vinyl aromatic hydrocarbon-based resin is 0.1/99.9 to 20/80; and a method for producing the same.

Description

  The present invention relates to a copolymer having a branched structure and a copolymer composition.

  By using a divinylbenzene derivative, a copolymer composition having a branched structure can be synthesized. When a branched structure is formed by anionic polymerization of a divinylbenzene derivative, it can be roughly divided into two depending on the polymerization order of the divinylbenzene derivative.

  One is a method of first synthesizing a core having a branched structure (Core First method), and a method in which a vinyl aromatic hydrocarbon monomer or the like is polymerized after anionic polymerization of a divinylbenzene derivative (patent) Document 1, Non-Patent Document 1) and methods (Patent Documents 2 and 3) of polymerizing vinyl aromatic hydrocarbon monomers after anionic copolymerization of divinylbenzene derivatives and other monomers are known. Yes.

The other is a method in which a polymer chain (Arm) to be branched is polymerized first (Arm First method), and a vinyl aromatic hydrocarbon monomer or the like is polymerized and then a divinylbenzene derivative is anionically polymerized. A method (Patent Documents 4 to 6), a method of polymerizing a vinyl aromatic hydrocarbon monomer and the like, anion polymerization of a divinylbenzene derivative, and a polymerization of another monomer (Patent Documents 7 and 8). Are known.

JP-A-3-79606 Japanese National Patent Publication No. 11-513715 JP-T-2004-517202 Japanese Patent Laid-Open No. 10-25395 JP 2010-255008 A JP 2001-139647 A Japanese National Patent Publication No. 8-504865 JP-A-8-81514

H. Eschwey et al. “Starpolymers from styrene and divinylbenzene”, Polymer, 1975, Vol. 16, p. 180

An object of the present invention is to provide a copolymer and a copolymer composition having a novel branched structure for improving the moldability of a resin.

  That is, the present invention is obtained by (1) anionic polymerization of a vinyl aromatic hydrocarbon monomer using an initiator having a molar ratio of divinylbenzene derivative to alkyllithium of 3/97 to 80/20. The polymer obtained by GPC method has a weight average molecular weight of 20,000 to 2,000,000, and a copolymer obtained by simultaneously adding a divinylbenzene derivative and a conjugated diene as a branching step, (2 ) Anionic polymerization of vinyl aromatic hydrocarbon monomer is carried out using an initiator having a molar ratio of divinylbenzene derivative and alkyllithium of 3/97 to 80/20, and the resulting polymer is obtained by GPC method. Copolymer having a weight average molecular weight of 20,000 to 2,000,000 and obtained by adding a divinylbenzene derivative as a branching step. , (3) The weight ratio of the copolymer according to (1) or (2) and the vinyl aromatic hydrocarbon resin is 0.1 / 99.9 to 20/80 Combined resin composition, (4) An anionic polymer of vinyl aromatic hydrocarbon monomer is obtained by GPC method using an initiator having a molar ratio of divinylbenzene derivative to alkyllithium of 3/97 to 80/20. And a copolymer obtained by simultaneously adding a divinylbenzene derivative and a conjugated diene or a divinylbenzene derivative as a branching step, wherein the weight average molecular weight is 20,000 to 2,000,000. Is the method.

  Since the copolymer and copolymer resin composition having a branched structure of the present invention have a high melt tension and a high strain-hardening property, the cell diameter can be easily uniformed during foam molding. it can.

In this specification, the divinylbenzene derivative means 1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-diisopropenylbenzene, 1,4-diisopropenylbenzene, m-isopropenylstyrene, p. -Isopropenyl styrene and the like, preferably 1,3-divinylbenzene and 1,4-divinylbenzene. You may use these divinylbenzene derivatives as a 1 type, or 2 or more types of mixture.

In the present specification, the alkyl lithium includes n-butyl lithium, sec-butyl lithium, tert-butyl lithium, ethyl lithium, 1,1-diphenylhexyl lithium, and preferably n-butyl lithium.

The molar ratio of the divinylbenzene derivative to the alkyl lithium is 3/97 to 80/20. If the effect of improving the melt tension and strain curability is greatly increased, the ratio is 15/85 to 50/50. When this ratio is less than 3/97, the effect of improving melt tension and strain curability is small.

In this specification, the vinyl aromatic hydrocarbon monomer is styrene, α-methylstyrene, α-ethylstyrene, o-methylstyrene, p-methylstyrene, o-ethylstyrene, p-ethylstyrene, p- Examples include tert-butyl styrene, 2,4-dimethyl styrene, 2,5-dimethyl styrene, p-tert-butoxy styrene, vinyl naphthalene, vinyl anthracene, and indene, and styrene is preferable.

  When an anionic polymerization of a vinyl aromatic hydrocarbon monomer is carried out using an initiator composed of a divinylbenzene derivative and an alkyl lithium, a mixture of linear, linear double molecular weight, star, etc. is obtained ( Anionic polymer before branching process).

When an anionic polymer from a divinylbenzene derivative and an alkyl lithium is branched (branching step), a Pom-Pom type (Star-Linear-Star type) in which two linear, star, and star shapes are connected, A mixture such as a shape in which three or more molds are connected (star-Linear-Star-Linear-Star) is obtained. On the other hand, when the anionic polymer before the branching process is synthesized without using a divinylbenzene derivative and branched, only a linear and star shape can be obtained.

Examples of the conjugated diene include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, 1,3-cyclohexadiene, and the like. Is 1,3-butadiene or isoprene.

The rate constant of the reaction between the isoprene anion conjugated diene and the divinylbenzene derivative divinylbenzene is 1/10 or less compared to the rate constant of the divinylbenzene anion and divinylbenzene (ANIONIC POLYMERISATION PRINCIPLES AND PRACTICAL APPLICATIONS, MARCEL DEKKER, INC., 1996, p337)). Therefore, in the branching process, the divinylbenzene chain tends to be long, tends to be multi-branched, and tends to have a high molecular weight.

A copolymer having a branched structure can be used only as a copolymer, but can also be used by kneading with a vinyl aromatic hydrocarbon resin. Thereby, compared with the vinyl aromatic hydrocarbon resin before kneading | mixing, melt tension and distortion sclerosis | hardenability improve, and it becomes easy to obtain a uniform cell at the time of foam molding.

In this specification, the vinyl aromatic hydrocarbon resin means polystyrene, poly (α-methylstyrene), poly (α-ethylstyrene), poly (o-methylstyrene), poly (p-methylstyrene), poly ( o-ethylstyrene), poly (p-ethylstyrene), poly (p-tert-butylstyrene), poly (2,4-dimethylstyrene), poly (2,5-dimethylstyrene), poly (p-tert- Butoxystyrene), polyvinyl naphthalene, polyvinyl anthracene, polyindene and the like, and polystyrene is preferable.

The mass ratio of the copolymer of the present invention and the vinyl aromatic hydrocarbon resin is 0.1 / 99.9 to 20/80, preferably 0.5 / 99.5 to 20/80. When the mass ratio of the copolymer is less than 0.1, the effect of improving the melt tension and strain curability is small, and when it is more than 20, the melt tension becomes too large and the moldability is deteriorated, which is not preferable.

The weight average molecular weight of the anionic polymer before the branching step of the present invention indicates the weight average molecular weight of the peak portion of the molecular weight distribution curve measured by gel permeation chromatography (hereinafter referred to as GPC). This is obtained from a calibration curve obtained by measuring GPC of standard polystyrene having a known molecular weight, obtaining a retention capacity at the peak position, and drawing a correlation curve between the weight average molecular weight and the retention capacity.

The weight average molecular weight of the anionic polymer before the branching step of the present invention is 20,000 to 2,000,000, preferably 40,000 to 1,500,000, more preferably 100,000 to 1. , 500,000. The molecular weight between entanglement points of the anionic polymer of styrene, which is a vinyl aromatic hydrocarbon monomer, is about 20,000 (Non-Patent Document: Physical. Chem., 1968, vol. 349, p. 433) and branched. The viscoelastic property of the polymer having a large influence is exerted when the molecular weight of the branch is 2 times or more of the molecular weight between the entanglement points, and when the molecular weight appears more than 5 times. Therefore, when the weight average molecular weight is less than 20,000, the entanglement becomes insufficient, and when it is 40,000, the molecular weight between the entanglement points becomes twice, so that the entanglement becomes easy. On the other hand, if it exceeds 2,000,000, the moldability is remarkably deteriorated.

The melt tension (melt tension) is a tension generated when a heated and melted resin is pulled. While melt flow rate is an index of viscosity, it is used as a primary evaluation of moldability such as spinnability and blow moldability as an index of elasticity. When the melt tension is low, the resin tends to sag in the blown film molding and the drawdown property is deteriorated, and the foam is easily broken in the foam molding. Conversely, if the melt tension is too high, it tends to break during high speed molding.

The elongational viscosity is the viscosity under elongational deformation of the molten resin at a constant strain rate and a constant temperature. Elongation viscosity is used as a method for evaluating the ease of deformation under the free surface after exiting a die such as melt spinning, film molding, blow molding, and thermoforming.

Strain hardenability is an elastic phenomenon in which deformation resistance increases rapidly as strain increases in elongation deformation. It is known that when the strain hardenability is remarkable, uneven thickness hardly occurs, so that the deformation occurs uniformly. As a result, foam formability is improved because a sheet having a uniform thickness is easily obtained, and bubble breakage in bubble growth is reduced.

In the strain hardening property, the elongation viscosity at a stretching ratio e ¹ times (e is a Napier constant) is η ₁ , the elongation viscosity at a stretching ratio e ² times is η _2, and the ratio η ₂ / η ₁ of the elongation viscosity is Use as an indicator.

The strain-hardening ratio is a problem of the degree of increase from the strain-hardening property of the vinyl aromatic hydrocarbon resin to be used, so the copolymer resin composition comprising the copolymer and the vinyl aromatic hydrocarbon-based resin The ratio of the extension viscosity η ₂ / η ₁ and the ratio of the extension viscosity of the vinyl aromatic hydrocarbon resin η ₂ / η ₁ were used.

EXAMPLES The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

<Kneading method>
Kneading was performed by two kinds of methods. The first method was performed using a Brabender Plasticorder PL2000 (kneader attachment: internal volume 60 mL, two sigma blades) at a mixing bath temperature of 200 ° C., a blade rotation speed of 70 rpm, and a kneading time of 10 minutes. . The second method was extrusion and pellets obtained at a temperature of 200 ° C. using a 40 mmφ extruder (single screw dull screw) manufactured by Tabata Corporation.

  The resin to be kneaded is a synthesized copolymer and polystyrene of vinyl aromatic hydrocarbon resin. As the polystyrene, HRM-10N manufactured by Toyo Styrene Co., Ltd. was used. For example, in a 10% by mass kneaded product, 5 g of the synthesized copolymer and 45 g of HRM-10N were used.

<Measurement method>
The melt tension was measured using a Capillograph 1D (capillary dimension: diameter 1 mm, length 40 mm, barrel dimension: diameter 9.55 mm, effective length 250 mm) manufactured by Toyo Seiki Co., Ltd. About 25 g of the pellet-shaped sample was packed in a barrel and preheated at a barrel temperature of 200 ° C. for 3 minutes. Thereafter, the molten resin was extruded at a piston speed of 5 mm / min at 200 ° C., and the tension at the time of take-up at a take-up speed of 5 mm / min was described as the value of the melt tension.

The evaluation of strain curability used elongation viscosity, and the elongation viscosity was measured using a Meissner type elongation viscometer melten rheometer manufactured by Toyo Seiki Co., Ltd. A rod-like sample having a diameter of about 1 mm and a length of about 30 cm was melted in silicon oil, allowed to stand for 3 minutes, then measured by a method in which both ends were sandwiched between rotary clamps and stretched in a uniaxial direction. The measurement temperature was 140 ° C. and the elongation rate was 0.05 sec ⁻¹ .

  The weight average molecular weight was measured by using a differential refractometer at 40 ° C. with tetrahydrofuran as a solvent, using HLC-8220GPC (column: KF-404HQ manufactured by Showa Denko KK) manufactured by Tosoh Corporation. The weight average molecular weight was determined using SRM705A as a standard substance certified by the US National Institute of Standards and Technology.

<Manufacturing method>
Polymerization was carried out at a stirring speed of about 200 rpm using a MaxBlend blade with a stirring blade having a 3 L or 10 L internal volume. The inside of the can was purged with nitrogen, and the inside pressure of the can was set to atmospheric pressure or higher so that outside air could not enter. The raw materials were weighed from a dewatering can by nitrogen or measured in a glove box in a nitrogen atmosphere and added to the polymerization can by nitrogen. The raw materials are cyclohexane, styrene, divinylbenzene, n-butyllithium and isoprene.

<Dehydration method>
Cyclohexane, styrene, and divinylbenzene were dehydrated by bubbling nitrogen in a dehydration can (room temperature) and dehydrated until the water content was 10 ppm or less. Isoprene was dehydrated using vacuum dried 3A molecular sieves until the water content was 10 ppm or less.

[Example 1]
To a 10 L polymerization vessel, 5.67 kg of cyclohexane (indicated in the table as CHx-1) containing 300 ppm of tetrahydrofuran and 21.3 mg of divinylbenzene (indicated in the table as DVB-1) were added. Thereafter, the temperature was raised to 30 ° C., 23.1 mL of a cyclohexane solution containing n-butyllithium having a concentration of 0.236 mol / L (indicated in the table as BuLi) was added and reacted for 30 minutes. Next, after adding 10 g of styrene (indicated in the table as St-1) and reacting at 30 ° C. for 30 minutes, 600 g of styrene (indicated in the table as St-2) was further added. Polymerization was carried out for 1 hour at a temperature of 40 ° C. (anionic polymer before the branching step). This polymerization solution was sampled and the weight average molecular weight was measured by GPC. Furthermore, 15.7 g of divinylbenzene (the notation in the table is DVB-2) and 33.4 g of isoprene (the notation in the table is Isp) are 700 g of cyclohexane (the notation in the table is CHx-2). It was dissolved and added to a reaction vessel heated to 70 ° C. and reacted for 5 hours. The reaction was stopped with a small amount of water, and precipitation was performed by dropping the polymerization solution into methanol. 5 g of the obtained copolymer and 45 g of polystyrene (HRM-10N) were kneaded with a plastic coder PL2000 manufactured by Brabender, and the melt tension and elongational viscosity were measured. The measurement results are shown in Table 2.

[Examples 2 to 9]
The same operation as Example 1 was performed except the raw material mixing | blending shown in Table 1. The measurement results are shown in Table 2.

[Example 10]
The isoprene was not used, and except that, an anionic polymer before the branching step was synthesized and the weight average molecular weight was measured in the same manner as in Example 1. Thereafter, as in Example 1, a copolymer was synthesized using divinylbenzene, stopped and precipitated, and kneaded and measured. The amount of raw material used is shown in Table 3.

[Examples 11 and 12]
The same operation as in Example 10 was performed with the amount of raw materials shown in Table 1. The measurement results are shown in Table 3.

[Examples 13 and 14]
In Example 13, the copolymer obtained in Example 8 was used, and in Example 14, the copolymer obtained in Example 12 was used. Table 4 shows the resin composition with polystyrene (HRM-10N). Extrusion was carried out using a 40 mmφ extruder manufactured by Tabata Co., Ltd. at the stated quantity ratio.

[Comparative Examples 1 and 2]
Anionic polymer before the branching step was synthesized and the weight average molecular weight was measured in the same manner as in Example 1 except that divinylbenzene was not used. Similarly, a copolymer was synthesized using isoprene and divinylbenzene, stopped, precipitated, kneaded and measured. The amounts of raw materials used are shown in Table 1, and the measurement results are shown in Table 2.

[Comparative Examples 3 and 4]
Anionic polymer before the branching step was synthesized and the weight average molecular weight was measured in the same manner as in Example 1 except that divinylbenzene was not used. Thereafter, a copolymer was synthesized in the same manner without using isoprene, stopped and precipitated, and kneaded and measured. The amounts of raw materials used are shown in Table 1, and the measurement results are shown in Table 2.

In Table 3, the initiator ratio indicates each mol% of the divinylbenzene derivative and the alkyl lithium. However, since alkyllithium is inactivated by impurities in the solvent or monomer, it is not the amount used, but {used monomer M (g)} / {number average molecular weight Mn of polymer (g / mol). )} Is used.

The molecular weight is a weight average molecular weight obtained by a GPC method to determine the structure of the anionic polymer before the branching step.

The resins of the examples have improved melt tension and strain curability that affect foam moldability.

It has been found that the copolymer and copolymer composition having a branched structure of the present invention work effectively as a processing aid for foam molding. In addition, the present invention can be applied to the use of processing aids for sheets and foamed sheets.

Claims (4)

  Using an initiator having a molar ratio of divinylbenzene derivative to alkyllithium of 3/97 to 80/20, anionic polymerization of vinyl aromatic hydrocarbon monomer was performed, and the obtained polymer was determined by GPC method. A copolymer having a weight average molecular weight of 20,000 to 2,000,000 and obtained by simultaneously adding a divinylbenzene derivative and a conjugated diene as a branching step. Using an initiator having a molar ratio of divinylbenzene derivative to alkyllithium of 3/97 to 80/20, anionic polymerization of vinyl aromatic hydrocarbon monomer was performed, and the obtained polymer was determined by GPC method. A copolymer having a weight average molecular weight of 20,000 to 2,000,000 and obtained by adding a divinylbenzene derivative as a branching step.   The resin composition whose mass ratio of the copolymer of Claim 1 or 2 and vinyl aromatic hydrocarbon-type resin is 0.1 / 99.9-20 / 80. Using an initiator having a molar ratio of divinylbenzene derivative to alkyllithium of 3/97 to 80/20, an anionic polymer of vinyl aromatic hydrocarbon monomer has a weight average molecular weight determined by GPC method of 20,000. A method for producing a copolymer by simultaneously adding a divinylbenzene derivative and a conjugated diene, or a divinylbenzene derivative as a branching step.